Controlled combustion method for sugarcane bagasse ash: Performance and sustainability in durable concrete

Abstract

Declining fly ash availability and cement industry decarbonization imperatives necessitate alternative supplementary cementitious materials (SCMs). While sugarcane bagasse ash (SCBA) shows promise, uncontrolled mill combustion produces inconsistent quality with limited pozzolanic reactivity. This study develops a controlled combustion method using a custom-designed burner operating at 600–700°C with regulated airflow, systematically linking processing conditions to microstructure and concrete performance. Two variants were evaluated: uncontrolled mill ash (BA-M) and laboratory-controlled ash (BA-S). Characterization through XRD, FTIR, SEM-EDS, BET, and TGA confirmed that controlled burning significantly enhanced pozzolanic reactivity. BA-S exhibited 82.4% amorphous silica content, 3.1% loss on ignition, higher BET surface area (12.4 vs. 6.7 m²/g), and 60–70% portlandite consumption. At 10% cement replacement, BA-S concrete achieved 33% compressive strength increase, with 13.6% and 13.3% improvements in flexural and split tensile strengths. Durability enhancements were substantial: chloride permeability decreased 43%, sulphate resistance improved (93.6% vs. 88.1% strength retention), and acid attack resistance increased (15.0% vs. 24.1% strength loss). Water absorption and sorptivity reduced by 18% and 21%, confirming microstructural densification. Life-cycle assessment demonstrated 8% CO₂ reduction and 7% lower embodied energy. Despite higher processing costs, superior performance-durability synergy justifies adoption in aggressive-exposure applications. This study positions controlled-combustion SCBA as a viable alternative SCM, enabling simultaneous decarbonization and circular economy integration. © 2026 Elsevier Ltd.